Copper is the most common ingredient in waterborne preservatives and provides excellent activity against most fungi and insects. However, issues associated with copper migration from treated wood have created increasing concerns about potential risks to non-target organisms in surrounding environments, especially those in sensitive aquatic environments. Various Best Management Practices (BMPs) that can help produce clean and residue-free wood have been developed to minimize potential chemical leaching into the surrounding environment.
The effects of various BMPs were assessed by examining the copper concentrations in runoff from boards subjected to a given BMP and exposed to simulated rainfall for up to 9 hours. The results suggested that BMP method markedly affected the rate of copper losses from boards treated with ACZA, CA or ACQ. Copper losses in runoff tended to be highest during the initial rainfall exposure and then decreased to background levels. Air seasoning or kiln drying were associated with lower copper losses from boards treated
with ACZA, while those steamed for 6 hours were associated with higher copper losses. Increasing ACZA retentions were associated with exponentially higher copper losses. Hot water or ammonia bathes were associated with lower copper losses from boards treated with CA or ACQ. Increasing hot water bath time from 1 to 3 hours or decreasing ammonia bath time from 3 to 1 hours tended to decrease copper losses. These results suggest that BMPs are not uniformly effective on all treatments.